Research On Precision Drilling Technology Based On Crawling Robot

Successes of ARJ's maiden flight and C919 assembly mean that the level of China's aerospace manufacturing industry has been raised to a new dimension. Aircraft assembly is the most important technology in the aircraft manufacturing process. According to statistics, 50% to 70% of the time and cost of aircraft manufacturing process were spent on the aircraft assembly. Due to the large amount of assembly holes, the plane fatigue life heavily depends on the manufacturing quality of fastener holes, while automatic drilling can effectively improve the traditional method. This thesis investigates precision drilling on the crawling robot. The contents are as follow:(1) An online model, which can automatically modify the holes' coordinates, is developed to meet the request of high position accuracy of fastener holes. In specifics, the holes' position are modified firstly by spatial rotation matrix for monitoring double pre-assembly holes based on single curvature skin. For triple pre-assembly holes or more, the spatial transformation matrix of double curvature skin is calculated based on quaternions to modify the holes position online. At the same time, the RANSAC algorithm is also implemented to optimize the transformation matrix to eliminate the effect of outlier measurements.(2) To satisfy the perpendicularity of fastener holes, the method which detects the normal vector and compensation errors is put forward. The system is demonstrated based on four laser distance sensors, and a method is presented for modeling and correcting the error through analyzing the error sources. In addition, a close loop controller is also designed based on the position encoder to ensure the quality of countersinks.(3) Upon the demand for automatic assembly in aircraft production, a delicate multi-axis synchronous control system is designed for the crawling robot, including the hardware and software for the IPC+UMAC open control unit based on motion controller UMAC. The proposed methods are also validated by the crawling robot.Research on precision drilling technology in this paper has been verified experimentally. Under the same conditions, the precision drilling technology can effectively improve the position accuracy, perpendicularity and countersink depth dimensional accuracy.